(1) Field of the invention
During the study of limonene as a hand cleaner, it was found that limonene can be made bactericidal and fungicidal as was illustrated by the applicants in U.S. Pat. Nos. 5,153,229 and 5,229,425. A review of the literature showed that oxidized limonene contains several oxidation products including cis and trans-carveol, trans-p-menth-8-ene-1,2-diol, limonene 1,2-epoxide, limonene 8,9-epoxide, cis and trans-p-mentha-2,8-dien-1-ol, and perillyl alcohol, as was outlined by Blumann in Chemical Abstracts, Volume 63, 1965, on page 1819. The applicants decided to study other monocyclic monoterpenes for antimicrobial activity. Because limonene is not bactericidal and because the chemical structures of limonene and limonen-10-ol are identical except for a hydroxyl group replacing a hydrogen atom at carbon 10, the applicants were surprised to find that limonen-10-ol is bactericidal and fungicidal. A review showed that all the monocyclic monoterpenes that are known to be antimicrobial have an oxygen molecule or hydroxyl group replacing a hydrogen atom at carbons 2, 3, 4, or 8. Prior to the discovery by the applicants that perillyl alcohol is bactericidal, as demonstrated in U.S. Pat. No. 5,110,832, and menth-1-en-9-ol is bactericidal and fungicidal as outlined in U.S. Pat. No. 5,294,645 no monocyclic monoterpene with an oxygen or a hydroxyl group at carbon 7, 9 or 10 was recognized as having antimicrobial activity. After the applicants discovered that perillyl alcohol is bactericidal, the applicants decided to study limonen-10-ol for antimicrobial activity and were pleasantly surprised to find that limonen-10-ol kills bacteria, yeast, and fungi in bactericidal and fungicidal concentrations.
The chemical structures of limonene and limonen-10-ol follow below. ##STR1##
Because limonene is not bactericidal nor fungicidal and because the chemical structures of limonene and limonen-10-ol are identical except for a hydroxyl group replacing a hydrogen atom at carbon 10, limonen-10-ol was not expected to be bactericidal and fungicidal. It should be noted in the structures of the monocyclic monoterpenes that follow, that none of the monocyclic monoterpenes that are known to be bactericidal, have an oxygen atom or a hydroxyl group at carbon 9 or 10 as can be appreciated in the structures of: perillyl alcohol, carveol, carvone, dihydrocarveol, dihydrocarvone pulegone, isopulegol, menthol, menthone, terpinen-4-ol, and a-terpineol which follow. ##STR2##
Limonen-10-ol is an oil with a fruity aroma that is soluble in alcohol and is miscible in oil. Although it is insoluble in water, it can be easily emulsified in water. It is poorly soluble in propylene glycol, and is almost insoluble in glycerine. Limonen-10-ol occurs naturally, but heretofore, it has not been used as a bactericide nor fungicide.
Limonen-10-ol is available commercially from the Aldrich Chemical Company, 940 Saint Paul Avenue, Milwaukee, Wis. 53233, catalogue number 21,841-3, and from George Majetich PhD, Department of Chemistry, University of Georgia, Athens, Ga. 30602. It is produced by a proprietary method of oxygenating d-limonene.
(2) Description of the Prior Art
Zuckerman studied the effect of auto-oxidized d-limonene on bacteria, and found it was weakly bacteriostatic, was unstable, and lost its bacteriostatic effect on keeping as was discussed in Nature 168:517 (1961). He never studied limonen-10-ol. Kurita investigated the fungicidal activity of several components of essential oils as was reported in Biol. Chem., 45(4), 945-952, 1981, but he never studied the antimicrobial activity of limonen-10-ol against bacteria, yeast nor fungi. Murdock and Allen showed the germicidal effect of sodium benzoate against yeast was enhanced by orange peel oil and d-limonene, as was outlined in Food Technology Vol 14, No 9, 1960, pages 441-5. They never studied the activity of limonen-10-ol against bacteria, yeast nor fungi. Kellner et al demonstrated that ethereal oils and some of their components have anti-bacterial activity as was reported in Arneimittel-Forechung, 5, 224-9, 1955. He confirmed that limonene is not bactericidal. He never studied limonen-10-ol for bactericidal nor fungicidal activity. Gauvreau showed a means of producing disinfecting compositions in U.S. Pat. No. 3,595,975 by combining cetyl pyridinium with terpenes to form antiseptics, but he never studied limonen-10-ol alone nor in combination with cetyl pyridinium hydrochloride. A. Morel revealed the sterilizing action of carveol, dihydrocarveol, and their ozonization products in Comp. Rend. Soc. Biol. Volume 115, pages 536-8 (1934). He demonstrated the bactericidal effect of carveol and dihydrocarveol, but he never studied the bactericidal nor fungicidal activity of limonen-10-ol. The applicants discovered that limonene can be made bactericidal and fungicidal by oxidation as was outlined in U.S, Pat. Nos. 5,153,229 and 5,229,425 but limonen-10-ol was never studied for bactericidal nor fungicidal activity and limonene-10-ol has never been identified in oxidized limonene.
It should be pointed out that drugs which are bactericidal are usually not fungicidal, and drugs which are fungicidal are usually not bactericidal. In addition, drugs which are bactericidal frequently promote the growth of yeast. Table A, which follows, exemplifies the bactericidal and fungicidal activity of several commonly used anti-bacterial, anti-yeast, and anti-fungal antibiotics.
TABLE A __________________________________________________________________________ ANTIBIOTIC ACTIVITY AGAINST ANTIBIOTICS Gm.sup.+ Bac Gm.sup.- Bac AFBact Yeast Fungi __________________________________________________________________________ A. ANTIBACTERIAL 1. Ampicillin YES YES NO NO NO 2. Cephalothin YES YES NO NO NO 3. Chloram- YES YES NO NO NO phenicol 4. Erythromycin YES NO NO NO NO 5. Ethambutol NO NO YES NO NO 6. Gentamicin YES YES NO NO NO 7. Isoniazid NO NO YES NO NO 8. Nitro- NO YES NO NO NO furantoin 9. Penicillin YES NO NO NO NO 10. Rifampin YES NO YES NO NO Streptomycin YES YES YES NO NO Sulfonamides NO YES NO NO NO Tetracycline YES YES NO NO NO Vancomycin YES YES NO NO NO B. ANTIYEAST 1. Nystatin NO NO NO YES NO 2. Gentian NO NO NO YES NO violet C. ANTIFUNGAL 1. Chlotri- NO NO NO YES YES mazole 2. Griseofulvin NO NO NO NO YES __________________________________________________________________________ Gm.sup.+ Bac = Gram Positive Bacteria, Gm.sup.- Bac = Gram Negative Bacteria, AFBac = Acid Fast Bacteria, YES = Kills Organism, NO = No Activity Against Organism
It should be noted from the table above that none of the anti-bacterial antibiotics kill yeast nor fungi, and none of the anti-yeast nor anti-fungal antibiotics kill bacteria. Thus, an anti-fungal or anti-yeast antibiotic is not expected to kill bacteria and an anti-bacterial antibiotic is not expected to kill yeast nor fungi. Anti-fungal antibiotics do not necessarily kill yeast and anti-yeast antibiotics do not necessarily kill fungi.